Mutations of complement factor I and potential mechanisms of neuroinflammation in acute hemorrhagic leukoencephalitis

Pediatric Immunodeficiency Caused by Complement Classical and Alternative Pathway Defects Due to a Homozygous CFI Variant: A Case Report

Complement factor I (CFI) deficiency is a rare primary immunodeficiency that disrupts the classical and alternative complement pathways, potentially causing severe recurrent infections and autoimmune manifestations in pediatric patients. However, the coexistence of both pathways in a pediatric patient is extremely uncommon. We report a seven-year-old patient with a rare primary immunodeficiency disorder who presented with recurrent middle ear infections, paronychia, gastrointestinal infections, and respiratory infections. Genetic testing revealed a previously unreported homozygous variant in the CFI gene (c.848A>G; p.D283G). Immunological testing showed a decrease in complement C3, CFI, and CFH levels in the patient. Interestingly, the patient presented with IgA vasculitis, with renal pathology showing deposits of immune complexes containing IgA, IgG, IgM, and C1q. By considering the child's condition and genetic test results, the child was treated symptomatically and received regular peritoneal dialysis treatment. Subsequently, the child's condition improved compared to before and was discharged from the hospital. This case highlights the importance of considering CFI deficiency in children with recurrent infections and abnormalities in both the classical and alternative complement pathways. Our findings expand the known phenotypic spectrum of CFI deficiency and contribute to understanding genotype-phenotype correlations in complement disorders.

The role of complement factor I rare genetic variants in age related macular degeneration in Finland

Age-related macular degeneration (AMD) is the leading cause of irreversible blindness in the developed world. The alternative pathway (AP) of complement has been linked to the pathogenesis of AMD. In particular, rare variants (RVs) in the complement factor I (CFI) gene encoding the Factor I (FI) protein confer increased AMD risk. The prevalence of CFI RVs are well characterised in European AMD, however little is known about other populations. The Finnish population underwent genetic restriction events which have skewed allele frequencies in unexpected ways. A series of novel or enriched CFI RVs were identified in individuals with dry AMD from the Finnish Biobank Cooperative (FINBB), but the relationship between these genotypes and contribution to disease was unclear. Understanding how RVs impact the ability of FI to regulate the complement system is important to inform mechanistic understanding for how different genotypes contribute to disease development. To explore this a series of in vitro assays were used to functionally characterise the protein products of 3 CFI RVs enriched in FINBB dry AMD, where no prior data were available. The G547R variant resulted in almost complete loss of both classical pathway and AP regulatory potential. The c.982 g>a variant encoding G328R FI perturbed an exon splice enhancer site which resulted in exon skipping and a premature stop codon in vitro and low levels of FI in vivo. Despite detailed analysis no defect in levels or function was demonstrated in T107A. Functional characterization of all Finnish CFI RVs in the cohort allowed us to demonstrate that in Finnish dry AMD, collectively the type 1 CFI RVs (associated with FI haploinsufficiency) were significantly enriched with odds ratio (ORs) of 72.6 (95% confidence interval; CI 16.92 to 382.1). Meanwhile, type 2 CFI RVs (associated with FI dysfunction) collectively conferred a significant OR of 4.97 (95% CI 1.522 to 15.74), and non-impaired or normal CFI RV collectively conferred an of OR 3.19 (95% CI 2.410 to 4.191) although this was driven primarily by G261D. Overall, this study for the first time determined the ORs and functional effect for all CFI RVs within a Geographic Atrophy (GA) cohort, enabling calculations of combined risk scores that underline the risk conferred by type 1 and 2 CFI RVs in GA/AMD.

CNS Inflammation as the First Sign of Complement Factor I Deficiency: A Severe Myelitis Treated With Intense Immunotherapy and Eculizumab

OBJECTIVES

Complement factor I (CFI) deficiency is a rare autosomal recessive inborn error of immunity. In this report, we highlight that complete CFI deficiency may present with isolated and severe CNS inflammation without associated systemic features nor prior non-CNS episodes. This inflammation may respond to complement blockade therapy.

METHODS

This is a case description of a young girl with severe longitudinal transverse myelitis treated with aggressive immunotherapy that included eculizumab. Published cases of CFI-associated CNS inflammation were reviewed and discussed.

RESULTS

A primary immunodeficiency panel revealed 2 germline pathogenic variants in the CFI gene. Further complement testing of the index case and her family confirmed complete CFI deficiency.

DISCUSSION

We describe a unique case of severe spinal inflammation secondary to complete CFI deficiency. Although rare, isolated CNS inflammation may be the primary manifestation of complete CFI deficiency. To halt the uncontrolled complement-mediated inflammation associated with CFI deficiency, prompt targeted blockade of the complement pathway using eculizumab may be life changing in the acute phase. Long-lasting blockade of the complement pathway is also essential to prevent relapse in this subgroup of patients.

Complement Factor I Gene Variant as a Treatable Cause of Recurrent Aseptic Neutrophilic Meningitis: A Case Report

Mutations in the complement factor I (CFI) gene have previously been identified as causes of recurrent CNS inflammation. We present a case of a 26-year-old man with 18 episodes of recurrent meningitis, who had a variant in CFI(c.859G>A,p.Gly287Arg) not previously associated with neurologic manifestations. He achieved remission with canakinumab, a human monoclonal antibody targeted at interleukin-1 beta.

Complement factor I: Regulatory nexus, driver of immunopathology, and therapeutic

Complement factor I (FI) is the nexus for classical, lectin and alternative pathway complement regulation. FI is an 88 kDa plasma protein that circulates in an inactive configuration until it forms a trimolecular complex with its cofactor and substrate whereupon a structural reorganization allows the catalytic triad to cleave its substrates, C3b and C4b. In keeping with its role as the master complement regulatory enzyme, deficiency has been linked to immunopathology. In the setting of complete FI deficiency, a consumptive C3 deficiency results in recurrent infections with encapsulated microorganisms. Aseptic cerebral inflammation and vasculitic presentations are also less commonly observed. Heterozygous mutations in the factor I gene (CFI) have been demonstrated to be enriched in atypical haemolytic uraemic syndrome, albeit with a very low penetrance. Haploinsufficiency of CFI has also been associated with decreased retinal thickness and is a strong risk factor for the development of age-related macular degeneration. Supplementation of FI using plasma purified or recombinant protein has long been postulated, however, technical difficulties prevented progression into clinical trials. It is only using gene therapy that CFI supplementation has reached the clinic with GT005 in phase I/II clinical trials for geographic atrophy.

Pearls & Oy-sters: Homozygous Complement Factor I Deficiency Presenting as Fulminant Relapsing Complement-Mediated CNS Vasculitis

A 36-year-old man presented multiple times with fever, headache, alteration of mental status, and focal neurologic deficits. MRI revealed extensive white matter lesions that were partially reversed between episodes. Workup revealed persistently low complement factor C3, low factor B, and absent alternative complement pathway activity. Biopsy revealed neutrophilic vasculitis. Genetic testing revealed a homozygous variant in complement factor I (CFI), which was thought to be pathogenic. CFI regulates complement-mediated inflammation, and deficiency in this factor leads to unchecked alternative pathway activity and decrease in C3 and factor B through consumption. The patient has remained stable since starting IL-1β inhibition. Complement factor I is a rare disorder that should be considered in patients with atypical relapsing neurologic disease associated with neutrophilic pleocytosis.

Two-year follow-up of a young male with possible acute hemorrhagic leukoencephalitis: A case report

RATIONALE

Acute hemorrhagic leukoencephalitis (AHLE) is a rare but fetal fulminant demyelinating disease of unknown etiology. It is commonly regarded as a severe variant of acute demyelinating encephalomyelitis (ADEM). Its rapid clinical deterioration and high mortality appeal to clinicians to attach importance to early diagnosis. Immunosuppressive therapy is the main management to attenuate the autoimmune process, but with varied response and prognosis.

PATIENT CONCERNS

A young male presented with moderate fever, headache and seizures after extraction of impacted teeth, and then deteriorated rapidly to deep coma. Initial magnetic resonance imaging (MRI) revealed multiple plaque-like lesions in bilateral cerebra, right thalamus and pontobulbar region with massive edematous swelling and multifocal small hemorrhagic foci. Inflammatory parameters in the peripheral blood were only mild higher with a pleocytosis in CSF.

DIAGNOSIS

His clinical presentation, laboratory evaluation and radiological features were consistent with a suspected diagnosis of AHLE.

INTERVENTIONS

He underwent pulse corticosteroids initially but failed to respond to it. However, his consciousness improved obviously when he was treated with multiple courses of intravenous injection of immunoglobulin (IVIG) combined with mycophenolate mofetil (MMF).

OUTCOMES

The patient regained consciousness gradually on day 180 and was in minimally conscious state (MCS) during the two-year follow-up.

LESSONS

AHLE presents distinctly from classical ADEM, and the situation may pose a diagnostic challenge. Clinicians should be vigilant in recognizing AHLE because of its rapid clinical deterioration and high mortality. We highlight the critical role of multimodal MRI, particularly susceptibility-weighted imaging (SWI) in the diagnosis of AHLE if cerebral biopsies are unavailable. Multiple courses of IVIG with MMF may be effective when early single pulse of corticosteroids fails. Individual who survives the initial insult may carry relatively good prognosis.

Rapid genome sequencing identifies novel variants in complement factor I

Complement factor I deficiency (CFID; OMIM #610984) is a rare immunodeficiency caused by deficiencies in the serine protease complement factor I (CFI). CFID is characterized by predisposition to severe pneumococcal infection, often in infancy. We report a previously healthy adolescent male who presented with respiratory failure secondary to pneumococcal pneumonia and severe systemic inflammatory response. Rapid genome sequencing (rGS) identified compound heterozygous variants in CFI in the proband, with a novel maternally inherited likely pathogenic variant, a single nucleotide deletion resulting in premature stop (c.1646del; p.Asn549ThrfsTer25) and a paternally inherited novel likely pathogenic deletion (Chr 4:110685580-110692197del).

Weston Hurst hemorrhagic leukoencephalitis: A novel association with mixed connective tissue disease: uncloaking the “unholy” etiology underneath

Background

Weston Hurst syndrome (WHS), also known as acute hemorrhagic leukoencephalitis (AHLE), has not been previously associated with mixed connective tissue disease (MCTD), a rare rheumatologic disorder.

Case presentation

We report a case of a 35‐year‐old female who presented with deep coma with features of previously undiagnosed MCTD and responded favorably to intravenous immunoglobulin (IVIG) therapy. On detailed historical enquiry, clinical examination, and investigation, AHLE was diagnosed. Furthermore, our patient showed significant improvement with IVIG administration, even though initial steroid therapy was unsuccessful.

Conclusion

AHLE, an associated novel neurological manifestation of MCTD, can be responsive to IVIG, which makes this case reportable from the diagnostic as well as the therapeutic point of view.

The yin and the yang of early classical pathway complement disorders

The classical pathway of the complement cascade has been recognized as a key activation arm, partnering with the lectin activation arm and the alternative pathway to cleave C3 and initiate the assembly of the terminal components. While deficiencies of classical pathway components have been recognized since 1966, only recently have gain-of-function variants been described for some of these proteins. Loss-of-function variants in C1, C4, and C2 are most often associated with lupus and systemic infections with encapsulated bacteria. C3 deficiency varies slightly from this phenotypic class with membranoproliferative glomerulonephritis and infection as the dominant phenotypes. The gain-of-function variants recently described for C1r and C1s lead to periodontal Ehlers Danlos syndrome, a surprisingly structural phenotype. Gain-of-function in C3 and C2 are associated with endothelial manifestations including hemolytic uremic syndrome and vasculitis with C2 gain-of-function variants thus far having been reported in patients with a C3 glomerulopathy. This review will discuss the loss-of-function and gain-of-function phenotypes and place them within the larger context of complement deficiencies.

IL-1 and autoinflammatory disease: biology, pathogenesis and therapeutic targeting

Over 20 years ago, it was first proposed that autoinflammation underpins a handful of rare monogenic disorders characterized by recurrent fever and systemic inflammation. The subsequent identification of novel, causative genes directly led to a better understanding of how the innate immune system is regulated under normal conditions, as well as its dysregulation associated with pathogenic mutations. Early on, IL-1 emerged as a central mediator for these diseases, based on data derived from patient cells, mutant mouse models and definitive clinical responses to IL-1 targeted therapy. Since that time, our understanding of the mechanisms of autoinflammation has expanded beyond IL-1 to additional innate immune processes. However, the number and complexity of IL-1-mediated autoinflammatory diseases has also multiplied to include additional monogenic syndromes with expanded genotypes and phenotypes, as well as more common polygenic disorders seen frequently by the practising clinician. In order to increase physician awareness and update rheumatologists who are likely to encounter these patients, this review discusses the general pathophysiological concepts of IL-1-mediated autoinflammation, the epidemiological and clinical features of specific diseases, diagnostic challenges and approaches, and current and future perspectives for therapy.

Rare genetic causes of meningitis and encephalitis

Differential diagnosis of meningitis and encephalitis is often very challenging because it cannot be determined based on symptoms, and the diseases have various causes. This article explains rare genetic causes of meningitis and encephalitis. Autoinflammatory disorders include cryopyrin-associated periodic syndromes, familial Mediterranean fever, and tumor necrosis factor receptor-associated periodic syndrome. Furthermore, other genetic disorders, such as complement factor I deficiency, phosphatidylinositol glycan anchor biosynthesis class T mutation, and neuronal intranuclear inclusion disease, can present as meningitis and encephalitis.

Complement factor I deficiency: A potentially treatable cause of fulminant cerebral inflammation

Objective

To raise awareness of complement factor I (CFI) deficiency as a potentially treatable cause of severe cerebral inflammation.

Methods

Case report with neuroradiology, neuropathology, and functional data describing the mutation with review of literature.

Results

We present a case of acute, fulminant, destructive cerebral edema in a previously well 11-year-old, demonstrating massive activation of complement pathways on neuropathology and compound heterozygote status for 2 pathogenic mutations in CFI which result in normal levels but completely abrogate function.

Conclusions

Our case adds to a very small number of extant reports of this phenomenon associated with a spectrum of inflammatory histopathologies including hemorrhagic leukoencephalopathy and clinical presentations resembling severe acute disseminated encephalomyelitis. CFI deficiency can result in uncontrolled activation of the complement pathways in the brain resulting in devastating cerebral inflammation. The deficit is latent, but the catastrophic dysregulation of the complement system may be the result of a C3 acute phase response. Diagnoses to date have been retrospective. Diagnosis requires a high index of suspicion and clinician awareness of the limitations of first-line clinical tests of complement activity and activation. Simple measurement of circulating CFI levels, as here, may fail to diagnose functional deficiency with absent CFI activity. These diagnostic challenges may mean that the CFI deficiency is being systematically under-recognized as a cause of fulminant cerebral inflammation. Complement inhibitory therapies (such as eculizumab) offer new potential treatment, underlining the importance of prompt recognition, and real-time whole exome sequencing may play an important future role.

Acute Hemorrhagic Leukoencephalopathy: Pathological Features and Cerebrospinal Fluid Cytokine Profiles

BACKGROUND

Acute hemorrhagic leukoencephalopathy is a rare encephalopathy of unknown etiology, causing fulminant, hemorrhagic central nervous system demyelination with high mortality. It is unclear whether acute hemorrhagic leukoencephalopathy is an entirely distinct entity from acute disseminated encephalomyelitis.

PATIENTS AND METHODS

We report two patients with rapidly progressive neurological illness resulting in raised intracranial pressure and coma, with biopsy-proven acute hemorrhagic leukoencephalopathy (perivascular hemorrhages and demyelination, predominantly neutrophil infiltrates).

RESULTS

Acute cerebrospinal fluid showed pronounced T cell-associated cytokine elevation (interleukins 6, 8, and 17A) and CCL2 or CCL3, higher than in patients with acute disseminated encephalomyelitis, but no B cell-associated cytokine elevation.

CONCLUSION

Improved understanding of the immune process may provide rationale for use of anticytokine biologic agents.

Acute hemorrhagic leukoencephalitis of Weston Hurst secondary to herpes encephalitis presenting as status epilepticus: A case report and review of literature

Acute hemorrhagic leukoencephalitis (AHL) is a rare and mostly fatal fulminant demyelinating disease. This case describes a 63-year old male in status epilepticus associated with an intracerebral hemorrhage following a one week viral prodrome with rapid decline to coma. He exhibited peripheral leukocytosis, neutrophilic pleocytosis with normal glucose and high protein in cerebrospinal fluid (CSF). Additionally, CSF was positive for herpes simplex virus (HSV) polymerase chain reaction (PCR). Medical decompression, low-dose dexamethasone, antibiotics and acyclovir were initially given. Magnetic resonance imaging (MRI) was suggestive of AHL, thus he was treated with methylprednisolone 1 g/day for 5 days. The patient improved and was discharged with significant neurologic morbidity. This is the first reported case of AHL in the Philippines presenting as a diagnostic dilemma with a protracted clinical course who responded to high dose intravenous steroids.

Classical and Non-classical Presentations of Complement Factor I Deficiency: Two Contrasting Cases Diagnosed via Genetic and Genomic Methods

Deficiency of complement factor I is a rare immunodeficiency that typically presents with increased susceptibility to encapsulated bacterial infections. However, non-infectious presentations including rheumatological, dermatological and neurological disease are increasingly recognized and require a high-index of suspicion to reach a timely diagnosis. Herein, we present two contrasting cases of complement factor I deficiency: one presenting in childhood with invasive pneumococcal disease, diagnosed using conventional immunoassays and genetics and the second presenting in adolescence with recurrent sterile neuroinflammation, diagnosed via a genomic approach. Our report and review of the literature highlight the wide spectrum of clinical presentations associated with CFI deficiency and the power of genomic medicine to inform rare disease diagnoses.

Cutaneous Vasculitis and Recurrent Infection Caused by Deficiency in Complement Factor I

Cutaneous leukocytoclastic vasculitis arises from immune complex deposition and dysregulated complement activation in small blood vessels. There are many causes, including dysregulated host response to infection, drug reactions, and various autoimmune conditions. It is increasingly recognised that some monogenic autoinflammatory diseases cause vasculitis, although genetic causes of vasculitis are extremely rare. We describe a child of consanguineous parents who presented with chronic cutaneous leukocytoclastic vasculitis, recurrent upper respiratory tract infection, and hypocomplementaemia. A homozygous p.His380Arg mutation in the complement factor I (CFI) gene CFI was identified as the cause, resulting in complete absence of alternative complement pathway activity, decreased classical complement activity, and low levels of serum factor I, C3, and factor H. C4 and C2 levels were normal. The same homozygous mutation and immunological defects were also identified in an asymptomatic sibling. CFI deficiency is thus now added to the growing list of monogenic causes of vasculitis and should always be considered in vasculitis patients found to have persistently low levels of C3 with normal C4.

Neuroinflammation and Infection: Molecular Mechanisms Associated with Dysfunction of Neurovascular Unit

Neuroinflammation is a complex inflammatory process in the central nervous system, which is sought to play an important defensive role against various pathogens, toxins or factors that induce neurodegeneration. The onset of neurodegenerative diseases and various microbial infections are counted as stimuli that can challenge the host immune system and trigger the development of neuroinflammation. The homeostatic nature of neuroinflammation is essential to maintain the neuroplasticity. Neuroinflammation is regulated by the activity of neuronal, glial, and endothelial cells within the neurovascular unit, which serves as a “platform” for the coordinated action of pro- and anti-inflammatory mechanisms. Production of inflammatory mediators (cytokines, chemokines, reactive oxygen species) by brain resident cells or cells migrating from the peripheral blood, results in the impairment of blood-brain barrier integrity, thereby further affecting the course of local inflammation. In this review, we analyzed the most recent data on the central nervous system inflammation and focused on major mechanisms of neurovascular unit dysfunction caused by neuroinflammation and infections.

Mycoplasma pneumoniae, a trigger for Weston Hurst syndrome

Objective:

We report a case of Mycoplasma pneumoniae infection as one possible trigger for Weston Hurst syndrome (acute hemorrhagic leukoencephalitis), a rare disorder of microvascular injury often described as a postinfectious complication of an upper respiratory illness.

Methods:

This is a case of a 27-year-old man presenting with a Glasgow Coma Scale score of 3 and an acute head CT revealing extensive vasogenic edema in the right hemisphere associated with mass effect in the context of a recent upper respiratory illness. Right frontal biopsy was performed on day 2, which showed acute cerebritis, and the patient was aggressively treated with antibiotics. However, over the next 5 days from presentation, the vasogenic edema increased, leading ultimately to brain herniation and death.

Results:

A full autopsy was performed at 5 days from presentation, which showed areas of vessel wall fibrinoid necrosis throughout the right hemisphere as well as, but less so, in the left frontal lobe and pons. Chest x-ray on presentation revealed atypical pneumonia, blood tests were positive for cold agglutinins, and at full autopsy, there was myocarditis, all in keeping with recent M pneumoniae infection. DNA obtained from lung and diseased brain (postmortem) was positive for Mycoplasma providing more direct evidence for brain invasion by this organism as the ultimate trigger for Weston Hurst syndrome.

Conclusions:

This is a rare case report of Weston Hurst syndrome having both initial brain biopsy on day 2 and full autopsy results on day 5 of presentation revealing important clinical clues about the pathogenesis of this often fatal disorder.

CFI-rs7356506 polymorphisms associated with Vogt-Koyanagi-Harada syndrome

PURPOSE

Complement factor I (CFI) plays an important role in complement activation pathways and is known to affect the development of uveitis. The present study was performed to investigate the existence of an association between CFI genetic polymorphisms and Vogt-Koyanagi-Harada (VKH) syndrome.

METHODS

A total of 100 patients diagnosed with VKH syndrome and 300 healthy controls were recruited for the study. Two milliliters of peripheral blood were collected in a sterile anticoagulative tube. CFI-rs7356506 polymorphisms were genotyped using Sequenom MassARRAY technology. Allele and genotype frequencies were compared between patients and controls using a χ(2) test. The analyses were stratified for recurrent status, complicated cataract status, and steroid-sensitive status.

RESULTS

No significant association was found between CFI-rs7356506 polymorphisms and VKH syndrome. However, patients with recurrent VKH syndrome had lower frequencies of the G allele and GG homozygosity in CFI-rs7356506 when compared to the controls (p=0.016, odds ratio [OR]=0.429, 95% confidence interval [CI]=0.212-0.871; p=0.014, OR=0.364, 95% CI=0.158-0.837, respectively). Furthermore, there were significant decreases in the frequencies of the G allele and GG homozygosity in CFI-rs7356506 in patients with VKH syndrome with complicated cataract compared to the controls (p<0.001, OR=0.357, 95% CI=0.197-0.648; p<0.001, OR=0.273, 95% CI=0.135-0.551, respectively). Nevertheless, no significant association with patients with VKH syndrome in steroid-sensitive statuses was detected for CFI-rs7356506 polymorphisms.

CONCLUSIONS

Our results indicate that CFI polymorphisms are not significantly associated with VKH syndrome; nevertheless, we identified a trend for the association of CFI-7356506 with VKH syndrome that depends on the recurrent status and the complicated cataract status but not on the steroid-sensitive status.

Complement factor I from flatfish half-smooth tongue (Cynoglossus semilaevis) exhibited anti-microbial activities

Complement factor I (Cfi) is a soluble serine protease which plays a crucial role in the modulation of complement cascades. In the presence of substrate modulating cofactors (such as complement factor H, C4bp, CR1, etc), Cfi cleaves and inactivates C3b and C4b, thereby controlling the complement-mediated processes. In this study, we sequenced and characterized Cfi gene from Cynoglossus Semilaevis (designated as CsCfi) for the first time. The full-length cDNA of CsCfi was 2230 bp in length, including a 98 bp 5'-untranslated region (UTR), a 164 bp 3'-UTR and a 1968 bp open reading frame (ORF). It encoded a polypeptide of 656 amino acids, with a molecular mass of 72.28 kDa and an isoelectric point of 7.71. A signal peptide was defined at N-terminus, resulting in a 626-residue mature protein. Multiple sequence alignment revealed that Cfi proteins were well conserved with the typical modular architecture and identical active sites throughout the vertebrates, which suggested the conserved function of Cfi. Phylogenetic analysis indicated that CsCfi and the homologous Cfi sequences from teleosts clustered into a clade, separating from another clade from the cartilaginous fish and other vertebrates. Tissue expression profile analysis by quantitative real-time PCR (qRT-PCR) showed that CsCfi mRNA constitutively expressed in all tested tissues, with the predominant expression in liver and the lowest in stomach. Temporal expression levels of CsCfi after challenging with Vibrio anguillarum showed different expression patterns in intestine, spleen, skin, blood, head kidney and liver. The recombinant CsCfi (rCsCfi) protein showed broad-spectrum antimicrobial activities against the Gram-positive bacteria Staphylococcus aureus and the Gram-negative bacteria Escherichia coli, Pseudomonas aeruginosa and Shewanella putrefaciens. The research revealed that CsCfi plays an important role in C. Semilaevis immunity.

Canonical Nlrp3 inflammasome links systemic low-grade inflammation to functional decline in aging

Despite a wealth of clinical data showing an association between inflammation and degenerative disorders in the elderly, the immune sensors that causally link systemic inflammation to aging remain unclear. Here we detail a mechanism by which the Nlrp3 inflammasome controls systemic low-grade age-related "sterile" inflammation in both periphery and brain independently of the noncanonical caspase-11 inflammasome. Ablation of Nlrp3 inflammasome protected mice from age-related increases in the innate immune activation, alterations in CNS transcriptome, and astrogliosis. Consistent with the hypothesis that systemic low-grade inflammation promotes age-related degenerative changes, the deficient Nlrp3 inflammasome-mediated caspase-1 activity improved glycemic control and attenuated bone loss and thymic demise. Notably, IL-1 mediated only Nlrp3 inflammasome-dependent improvement in cognitive function and motor performance in aged mice. These studies reveal Nlrp3 inflammasome as an upstream target that controls age-related inflammation and offer an innovative therapeutic strategy to lower Nlrp3 activity to delay multiple age-related chronic diseases.